Little Help? Problems with 1969 40hp Evinrude

Discussion in 'Boats and Motors' started by Hoosier Daddy, Nov 6, 2008.

  1. I have an old 1969 Evinrude 40hp outboard. I have had the engine for three years and every year it has given me issues. I have had is serviced by two different mechanics and recently have attempted to fix it with the help of my machine designer father.

    Motor starts and runs. Sometimes it will slip out of gear as I throttle up from slower speeds to higher. All the sudden it will go from normal progression and then no longer be pushing the boat forward. I then lower the throttle and it kicks back in. Also it is leaking lower unit oil. We just replaced the seals on the lower unit.

    Any ideas or a point in the right direction would be much appreciated.

    Also it is a short shaft. I have been told that it is very tough to find short shafts these days in this horse power?
  2. UFM82

    UFM82 The one others want to be

    Outboard gearboxes work in a funky way IMHO. The Drive shaft sticks into the L/U between the forward and the reverse gear. The driven gear sits horizontally in relation to the ground. The forward and reverse gears sit vertically. When you shift the engine into gear, you move the shift linkage with in turn turns a cam in the L/U. The gears actually move into the driven gear. I'm trying to remember exactly how my old Merc L/U worked but I know that if the components in the L/U are worn, it can jump out of gear under load. The gears are cut so that they will actually "pull" themselves together under the load. When the teeth start to have excessive wear, that "pull" weakens and the gears can jump. I also seem to remember a spring in the L/U that held pressure against the gear carrier that assisted this. If the L/U is leaking oil it's a sign that water may have intruded into the case and has caused damage. I know that when shift cables get stiff and don't allow full movement they can cause incomplete gear engagement and cause the same thing. You may want to pull the L/U apart and inspect it. Pull the prop and then unscrew the large nut that screws into the case that holds the gear carrier in place. The downside is you'll have to drop the L/U so you can get the driveshaft out of the way I think. I'll have to do a little research on that to be certain.
    Drain the L/U first and look at the fluid- milky or cloudy is bad, brownish is terminal as that signifies rust. Rust is death on an L/U.


    Not much help.

  3. Is this motor an electric shift?. If it is it sounds like the coil spring or hub or shift control. If it is mechanical shift, check the prop. The hub may be spun or sheer pin broken.
  4. Sometime unused[unburned] oil draining out of the crankcase looks like lower unit leaks. Mike
  5. Thanks alot for all the input!!!!!!

    I will get to work and hopefully identify the problems.

    Much appreciated.
  6. Do you have a manual for the motor? If not, invest the $30 and get one.

    I have a Seloc manual which covers the 40hp Johnson back to 1971 and I owned one for a short time that may have been a '74. If the '69's are the same the lower unit housing on my motor split apart parallel to the prop shaft making them very easy to work on. You don't need any special tools or pullers like the modern motors. There are several seals, roller bearings, bushings, etc which may have worn causing some slop in keeping the gears engaged. I think on my motor I had to replace the clutch 'dog' and cradle which are moved by the shift yoke.

    The Seloc manual has a diagram and a pretty detailed description on how to rebuild the manual shift lower units from that era. Good luck.
  7. I have the manuals and also found online prints at Evinrudes website.

    We replaced some of the seals and bearings in the lower units a few months ago and you are correct it is relatively easy to get at and work on. My dad is the real brains behind the operation and I am anxious to see his response to the comments you guys have made so far. I think you will have definitely pointed him in the right direction.

    Thanks again and I will report back with results once we get a chance to tinker some more.
  8. Oh yeah.

    The fluid I drained out was greyish and pretty milky. You mnetioned that was bad. Care to ellaborate?

  9. UFM82

    UFM82 The one others want to be

    That shows signs of water intrusion but not horrible. If the fluid is brown it's because rust has set in and that's bad. If gray/milky, change it and fill it.
  10. ErieAngler

    ErieAngler Still Deadly w/ The Net


    I had the same motor. The LU's are not too hard to come by. Sounds to me like you may have a couple problems. 1 your gears are probably worn and sliping. 2 youre definately taking on water into your LU. 3 you may need to adjust your shift linkage. This can be done the easiest at the motor but also at the box. 4 you could be losing compression at higher speeds causing you to lose power.

    Most likely your gears are slipping - the easiest thing to do here is take the lower unit apart and check them out, including the clutch dog. UFM did a good job of describing how it all works. The funny thing with your motor is there is actually a pin that screws through your LU into the gear housing that holds your shifter linkage in place (this is located where most LU oil drain plugs are). These things are a pain in the )#$)** to put back together with one person and if you take it apart you might as well replace the seals (not too expensive). I picked up a LU a couple years ago for $100.

    2 since your oil is milky, water must be entering your gear case from either a crack, around the prop shaft, the seal around the LU (spliting the skeg section from the upper housing), or through the water pump. Most likely its around the water pump or prop shaft if the lower unit has never been torn apart. The seal around the prop shaft is an O ring. If you havent changed the water pump recently and plan on keeping the motor, you should buy a complete kit and that will ensure no leaks there.

    3 - see if you have any extra play in your shift linkage. This is unlikely the issue, but if there is little movement between your nuetral and fwd gear, it may be possible that the vibration from operating at hight speeds is vibrating the motor in and out of gear - but doubtful. Its always good to adjust this to the proper setting though.

    4 - i had a motor in the past that when operated at high speeds it actually decelerated in speed, but accelerated in rpms! ??confused?? when I tore apart the powerhead the piston rings were not creating a good seal against the cylinder walls and the result was at high speed it was causing the motor to lose compression. you could take the head off the motor (it uses a pressure gasket so you dont necessarily have to replace it and you dont have all the mess of cleaning) and check out the conditions of your rings. If you find problems with your powerhead, get rid of the motor, its not worth the money.

    Good luck.
  11. Fantastic info guys!!!!!

    Thanks for all the help.